chapter 7 body systems - lane community college · noninvasive hemodynamic monitoring assessments...

1Mosby items and derived items © 2011, 2006 by Mosby, Inc., an affiliate of Elsevier Inc.

Chapter 6

Cardiovascular System

Assessments


Cardiovascular System Assessments

Overview of essential components of this

chapter are the: Normal electrocardiogram (ECG) patterns

Common heart arrhythmias

Noninvasive hemodynamic monitoring

assessments

Invasive hemodynamic monitoring assessments

Determinants of cardiac output


The Electrocardiogram (ECG)


Figure 6-1. Electrocardiographic pattern of a normal cardiac cycle.

Insert Figure 6-1


Normal Heart Rates

Adult: 60 to 100 bpm

Infant: 130 to 150 bpm


Methods Used to Calculate

Heart Rates

When the rhythm is regular: Count the number of large boxes on the ECG strip

between two QRS complexes and then divide by

300.

For example, if an ECG strip consistently shows

four large boxes between each QRS complex, the

heart rate is 75 bpm. • 300 ÷ 4 = 75


Methods Used to Calculate

Heart Rates (Cont’d)

When the rhythm is irregular: The heart rate can be determined by counting the

QRS complexes on a 6-second strip and

multiplying by 10.


Common Heart

Arrhythmias


Sinus Bradycardia

In sinus bradycardia the heart rate is less

than 60 bpm.

Bradycardia means “slow heart.”

Sinus bradycardia has a normal P-QRS-T

pattern, and the rhythm is regular.


Figure 6-2. Sinus bradycardia. Rate is about 37 beats per minute.


Sinus Tachycardia

In sinus tachycardia the heart rate is greater

than 100 bpm.

Tachycardia means “fast heart.”

Sinus tachycardia has a normal P-QRS-T

pattern, and the rhythm is regular.


Figure 6-3. Sinus tachycardia. Rate is about 100 beats per minute.


Sinus Arrhythmia

In sinus arrhythmia the heart rate varies by

more than 10% from beat to beat.

The P-QRS-T pattern is normal, but the

interval between groups of complexes (e.g.,

R-R intervals) varies.


Figure 6-4. Sinus arrhythmia. Note the varying R-R interval.


Atrial Flutter

In atrial flutter the normal P wave is absent

and replaced by two or more regular saw-

tooth waves.

The QRS complex is normal, and the

ventricular rate may be regular or irregular.

The atrial rate is usually constant, 250 to 350

bpm, whereas the ventricular rate is in the

normal range.


Figure 6-5. Atrial flutter. Atrial rate is greater than 300 bpm; ventricular rate is

about 60 bpm.


Atrial Fibrillation

In atrial fibrillation the atrial contractions are

disorganized and ineffective, and the normal

P wave is absent.

The atrial rate ranges from 350 to 700 bpm.

The QRS complex is normal, and the

ventricular rate ranges from 100 to 200 bpm.


Figure 6-6. Atrial fibrillation.


Premature Ventricular Contractions

The premature ventricular contraction (PVC)

is not preceded by a P wave.

The QRS complex is wide, bizarre, and unlike

the normal QRS complex.

The regular heart rate is altered by a PVC.

The heart rhythm may be very irregular when

there are many PVCs.


Figure 6-7. Premature ventricular contraction.


Ventricular Tachycardia

In ventricular tachycardia, the P wave is

generally indiscernible and the QRS complex

is wide and bizarre in appearance.

The T wave may not be separated from the

QRS complex.

The ventricular rate ranges from 150 to 250

bpm.

The rate may be regular or slightly irregular.

Blood pressure is often decreased during

ventricular tachycardia.


Figure 6-8. Ventricular tachycardia.


Ventricular Flutter

In ventricular flutter the QRS complex has the

appearance of a wide sine wave. Regular, smooth, rounded wave

The rhythm is regular or slightly irregular.

The rate is 250 to 350 bpm.

There is usually not discernible peripheral

pulse associated with ventricular flutter.


Figure 6-9. Ventricular flutter.


Ventricular Fibrillation

Ventricular fibrillation is characterized by

chaotic electrical activity and cardiac activity.

The ventricles literally quiver out of control,

with no perfusion beat-producing rhythm.

The is no cardiac output or blood pressure. The patient will die in minutes without treatment.


Figure 6-10. Ventricular fibrillation and asystole.


Asystole (Cardiac Standstill)

Asystole is the complete absence of electrical

and mechanical activity.

Cardiac output stops, and the blood pressure

falls to zero.

The ECG tracing appears as a flat line.


Figure 6-10. Ventricular fibrillation and asystole.


Noninvasive Hemodynamic

Monitoring Assessments

Hemodynamics are defined as forces that

influence the circulation of blood.

The general hemodynamic status of the

patient can be monitored noninvasively at the

bedside by assessing the: Heart rate

Blood pressure

Perfusion state


Invasive Hemodynamic

Monitoring Assessments

Invasive hemodynamic monitoring is used in

the assessment and treatment of critically ill

patients. Invasive hemodynamic monitoring

includes: Intracardiac pressures and flows via a pulmonary

artery catheter

Arterial pressure via arterial catheter

Central venous pressure via a venous catheter


Pulmonary Artery Catheter

The pulmonary artery catheter (Swan-Ganz)

is a balloon-tipped, flow-directed catheter that

is inserted at the patient bedside.

Directly measures the: Right atrial pressure

Pulmonary artery pressure

Left atrial pressure

Cardiac output


Figure 6-11. Insertion of the pulmonary catheter.


Arterial Catheter

The most commonly used mode of invasive

hemodynamic monitoring

Measures: Continuous systolic, diastolic, and mean arterial

blood pressure

Fluctuations in blood pressure

Data for guidance of therapy decisions for

hypotension or hypertension


Central Venous Pressure Catheter

The central venous pressure catheter

measures the central venous pressure (CVP)

and right ventricular filling pressure.


Table 6-1. Hemodynamic Values Measured Directly


Table 6-2. Hemodynamic Values Calculated from Direct Hemodynamic Measurements


Table 6-3. Hemodynamic Changes Commonly Seen in Respiratory Diseases

chapter 7 body systems - lane community college · noninvasive hemodynamic monitoring assessments...

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